Detecting differences in root architecture and growth patterns among common bean (Phaseolus vulgaris L.) genotypes may provide unique selection criteria for genetic resistance to root rot caused by Fusarium solani (Mart) Sacc. f.sp. phaseoli (Burk.) W.C. Snyder & H.M. Hans. The pathogen infection acts to reduce root density by killing roots and may attenuate the functional efficiency of the remaining infected roots, leading to yield loss. When the primary root dies due to infection, promoting lateraland adventitious roots may contribute to plant survival in the presence of root rot organisms (Snapp et al., 2003). Understanding mechanisms of Fusarium root rot resistance in common bean, especially kidney beans, is a major goal of breeding programs. Quantitative information on root system traits associated with root rot resistance would improve selection criteria. Moreover knowledge of the genetic determinants of root traits and how they influence yield would allow for a more targeted breeding approach utilizing technologies such as QTL analysis. The objectives of this study were to: 1) characterize genetic variation of root architecture in contrasting bean classes expected to vary in reaction to Fusarium root rot and root system traits, under field and greenhouse conditions; and 2) identify root system characteristics that may be associated to root rot resistance in common bean.
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